Disperse azo dyes having an N-alkyl-phthalimide diazo component and an aniline coupling component have been known for a long time and are used in the dyeing of hydrophobic fibre materials. It has been found, however, that the dyeings or prints obtained using the dyes known at present do not in all cases meet current requirements, especially with regard to their fastness properties in respect of light, washing and perspiration. Particularly in the field of blue dyes there is a need for new dyes that give dyeings in brilliant shades having good fastness properties in respect of light, washing and perspiration.
It has now been found, surprisingly, that the dyes according to the invention meet the criteria mentioned above to a great extent.